Question

Pentru 3 stilouri si 4 pixuri s-au platit 138 de lei.Cat costa fiecare obiect daca 2 stilouri costa cat 5 pixuri?

Answer 1

$s=stilou \\ p=pix \\ 3s+4p=138lei \\ 6s+8p=276lei \\ 6s \to Costa~cat~15~pixuri \\ 2s=5p \\ Inlocuim ~in~:6s+8p=276lei \\ 15p+8p=276lei \\ 23p=276lei \\ p=276:23 \\ p=12lei(costa~un~pix) \\ 5~pixuri~costa:60lei(5*12) \\ 2~stilouri~ \to 1~stilou=60:2=30~lei.$